1. Field of the Invention
The present invention relates to a repeater in a transmission link for transmitting digital signals using time-division multiplexing, including a circuit for branching time slots from the incoming time-division multiplex signal.
2. Description of the Prior Art
A transmission link serves, for example, to transmit digital telephone and data signals having a bit sequence rate of 64 kbit/s. When combined into a time-division multiplex signal with 32 time slots, they are transmitted at a bit sequence rate of 2048 kbit/s. The transmission link includes repeaters at which individual time slots are branched. Repeaters are also provided in which the branched time slots or a portion of the branched time slots are re-injected.
Such a repeater, referred to as a branch device, is known from "telcom report", 10 (1987) Special "Multiplex- und Leitungseinrichtungen" (Multiplexing and line transmission equipment), pages 43-50.
This repeater gives an alarm when errors or disturbances occur in the time-division multiplex signal to be transmitted, for instance if a specific bit error ratio is exceeded. If this error is detected in the repeater or if an incoming digital signal fails to appear, an alarm signal is transmitted in the transmission direction. The transmission of information is, however, interrupted if an alarm is triggered by a repeater itself.